The present invention is directed to the field of machining. More particularly, a sine bar with a fixed pivot axis which eliminates the need for complex mathematical calculations/use of trig tables to compute a sharp corner height when machining and measuring parts.
Existing sine bars used to measure the sharp corner height when machining/checking a part, pivot about an axis that changes elevation and requires the use of complicated mathematical formulae of look up tables to adjust for this elevational change. Such calculations slow the machining process and, depending on the level of mathematical acuity and alertness of the machinist, can result in machining errors leading to significant increases in scrap parts.
The present invention introduces an improved sine bar assembly in which the pivot axis of the sine plate remains fixed and obviates the use of trig formulae/look up tables. The sine bar assembly of the present invention comprises a) a base plate; b) an L-shaped sine plate with a pivot axis in the region of a juncture formed by a first laterally extending arm and a second vertically extending arm; c) mounting means for supporting the L-shaped sine plate enabling the sine plate to pivot about the pivot axis; whereby the pivot axis remains at a fixed height and mathematical calculations necessary to determine a sharp corner height for other sine bars are obviated. Preferably, the sine bar has a smooth radiused surface on an outside of the juncture between the first arm and the second arm. The mounting means preferably includes first and second side plates, each side plate having at least one first opening facilitating attachment of the side plate to the base plate and at least one second opening for receiving a fastener which serves as an axle about which the sine bar pivots. The second opening in each side plate is kidney shaped defining a smooth arc with a radius generally equal to a radius forming the smooth arcuate surface on the L-shaped arm.
Various other features, advantages, and characteristics of the present invention will become apparent after a reading of the following detailed description.